In recent years, a technology of searching for certain information among a large amount of information using a mobile phone, a car navigation device, a personal computer or a Web server computer has become widespread. When conducting a search, the user enters a keyword using a keyboard or a voice entry system. In the case of voice entry, a voice recognition process is performed. Though the voice recognition technology has been improved year by year in its accuracy, the recognition rate thereof still remains at a low level, causing a problem of inconvenience. To solve the problem, the vehicle-mounted voice recognition apparatus disclosed in Japanese Laid-Open Patent Publication No. 2006-349427 discusses a technology for storing travelling history of a vehicle and creating a voice recognition dictionary for each driver based on the stored travelling history.